kernel/time/alarmtimer.c

   1 /*
   2  * Alarmtimer interface
   3  *
   4  * This interface provides a timer which is similarto hrtimers,
   5  * but triggers a RTC alarm if the box is suspend.
   6  *
   7  * This interface is influenced by the Android RTC Alarm timer
   8  * interface.
   9  *
  10  * Copyright (C) 2010 IBM Corperation
  11  *
  12  * Author: John Stultz <john.stultz@linaro.org>
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License version 2 as
  16  * published by the Free Software Foundation.
  17  */
  18 #include <linux/time.h>
  19 #include <linux/hrtimer.h>
  20 #include <linux/timerqueue.h>
  21 #include <linux/rtc.h>
  22 #include <linux/alarmtimer.h>
  23 #include <linux/mutex.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/posix-timers.h>
  26 #include <linux/workqueue.h>
  27 #include <linux/freezer.h>
  28
  29 /**
  30  * struct alarm_base - Alarm timer bases
  31  * @lock:               Lock for syncrhonized access to the base
  32  * @timerqueue:         Timerqueue head managing the list of events
  33  * @gettime:            Function to read the time correlating to the base
  34  * @base_clockid:       clockid for the base
  35  */
  36 static struct alarm_base {
  37         spinlock_t              lock;
  38         struct timerqueue_head  timerqueue;
  39         ktime_t                 (*gettime)(void);
  40         clockid_t               base_clockid;
  41 } alarm_bases[ALARM_NUMTYPE];
  42
  43 /* freezer delta & lock used to handle clock_nanosleep triggered wakeups */
  44 static ktime_t freezer_delta;
  45 static DEFINE_SPINLOCK(freezer_delta_lock);
  46
  47 static struct wakeup_source *ws;
  48
  49 #ifdef CONFIG_RTC_CLASS
  50 /* rtc timer and device for setting alarm wakeups at suspend */
  51 static struct rtc_timer         rtctimer;
  52 static struct rtc_device        *rtcdev;
  53 static DEFINE_SPINLOCK(rtcdev_lock);
  54
  55 /**
  56  * alarmtimer_get_rtcdev - Return selected rtcdevice
  57  *
  58  * This function returns the rtc device to use for wakealarms.
  59  * If one has not already been chosen, it checks to see if a
  60  * functional rtc device is available.
  61  */
  62 struct rtc_device *alarmtimer_get_rtcdev(void)
  63 {
  64         unsigned long flags;
  65         struct rtc_device *ret;
  66
  67         spin_lock_irqsave(&rtcdev_lock, flags);
  68         ret = rtcdev;
  69         spin_unlock_irqrestore(&rtcdev_lock, flags);
  70
  71         return ret;
  72 }
  73 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
  74
  75 static int alarmtimer_rtc_add_device(struct device *dev,
  76                                 struct class_interface *class_intf)
  77 {
  78         unsigned long flags;
  79         struct rtc_device *rtc = to_rtc_device(dev);
  80
  81         if (rtcdev)
  82                 return -EBUSY;
  83
  84         if (!rtc->ops->set_alarm)
  85                 return -1;
  86         if (!device_may_wakeup(rtc->dev.parent))
  87                 return -1;
  88
  89         spin_lock_irqsave(&rtcdev_lock, flags);
  90         if (!rtcdev) {
  91                 rtcdev = rtc;
  92                 /* hold a reference so it doesn't go away */
  93                 get_device(dev);
  94         }
  95         spin_unlock_irqrestore(&rtcdev_lock, flags);
  96         return 0;
  97 }
  98
  99 static inline void alarmtimer_rtc_timer_init(void)
 100 {
 101         rtc_timer_init(&rtctimer, NULL, NULL);
 102 }
 103
 104 static struct class_interface alarmtimer_rtc_interface = {
 105         .add_dev = &alarmtimer_rtc_add_device,
 106 };
 107
 108 static int alarmtimer_rtc_interface_setup(void)
 109 {
 110         alarmtimer_rtc_interface.class = rtc_class;
 111         return class_interface_register(&alarmtimer_rtc_interface);
 112 }
 113 static void alarmtimer_rtc_interface_remove(void)
 114 {
 115         class_interface_unregister(&alarmtimer_rtc_interface);
 116 }
 117 #else
 118 struct rtc_device *alarmtimer_get_rtcdev(void)
 119 {
 120         return NULL;
 121 }
 122 #define rtcdev (NULL)
 123 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
 124 static inline void alarmtimer_rtc_interface_remove(void) { }
 125 static inline void alarmtimer_rtc_timer_init(void) { }
 126 #endif
 127
 128 /**
 129  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
 130  * @base: pointer to the base where the timer is being run
 131  * @alarm: pointer to alarm being enqueued.
 132  *
 133  * Adds alarm to a alarm_base timerqueue
 134  *
 135  * Must hold base->lock when calling.
 136  */
 137 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 138 {
 139         if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
 140                 timerqueue_del(&base->timerqueue, &alarm->node);
 141
 142         timerqueue_add(&base->timerqueue, &alarm->node);
 143         alarm->state |= ALARMTIMER_STATE_ENQUEUED;
 144 }
 145
 146 /**
 147  * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
 148  * @base: pointer to the base where the timer is running
 149  * @alarm: pointer to alarm being removed
 150  *
 151  * Removes alarm to a alarm_base timerqueue
 152  *
 153  * Must hold base->lock when calling.
 154  */
 155 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
 156 {
 157         if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
 158                 return;
 159
 160         timerqueue_del(&base->timerqueue, &alarm->node);
 161         alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
 162 }
 163
 164
 165 /**
 166  * alarmtimer_fired - Handles alarm hrtimer being fired.
 167  * @timer: pointer to hrtimer being run
 168  *
 169  * When a alarm timer fires, this runs through the timerqueue to
 170  * see which alarms expired, and runs those. If there are more alarm
 171  * timers queued for the future, we set the hrtimer to fire when
 172  * when the next future alarm timer expires.
 173  */
 174 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 175 {
 176         struct alarm *alarm = container_of(timer, struct alarm, timer);
 177         struct alarm_base *base = &alarm_bases[alarm->type];
 178         unsigned long flags;
 179         int ret = HRTIMER_NORESTART;
 180         int restart = ALARMTIMER_NORESTART;
 181
 182         spin_lock_irqsave(&base->lock, flags);
 183         alarmtimer_dequeue(base, alarm);
 184         spin_unlock_irqrestore(&base->lock, flags);
 185
 186         if (alarm->function)
 187                 restart = alarm->function(alarm, base->gettime());
 188
 189         spin_lock_irqsave(&base->lock, flags);
 190         if (restart != ALARMTIMER_NORESTART) {
 191                 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 192                 alarmtimer_enqueue(base, alarm);
 193                 ret = HRTIMER_RESTART;
 194         }
 195         spin_unlock_irqrestore(&base->lock, flags);
 196
 197         return ret;
 198
 199 }
 200
 201 ktime_t alarm_expires_remaining(const struct alarm *alarm)
 202 {
 203         struct alarm_base *base = &alarm_bases[alarm->type];
 204         return ktime_sub(alarm->node.expires, base->gettime());
 205 }
 206 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
 207
 208 #ifdef CONFIG_RTC_CLASS
 209 /**
 210  * alarmtimer_suspend - Suspend time callback
 211  * @dev: unused
 212  * @state: unused
 213  *
 214  * When we are going into suspend, we look through the bases
 215  * to see which is the soonest timer to expire. We then
 216  * set an rtc timer to fire that far into the future, which
 217  * will wake us from suspend.
 218  */
 219 static int alarmtimer_suspend(struct device *dev)
 220 {
 221         struct rtc_time tm;
 222         ktime_t min, now;
 223         unsigned long flags;
 224         struct rtc_device *rtc;
 225         int i;
 226         int ret;
 227
 228         spin_lock_irqsave(&freezer_delta_lock, flags);
 229         min = freezer_delta;
 230         freezer_delta = ktime_set(0, 0);
 231         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 232
 233         rtc = alarmtimer_get_rtcdev();
 234         /* If we have no rtcdev, just return */
 235         if (!rtc)
 236                 return 0;
 237
 238         /* Find the soonest timer to expire*/
 239         for (i = 0; i < ALARM_NUMTYPE; i++) {
 240                 struct alarm_base *base = &alarm_bases[i];
 241                 struct timerqueue_node *next;
 242                 ktime_t delta;
 243
 244                 spin_lock_irqsave(&base->lock, flags);
 245                 next = timerqueue_getnext(&base->timerqueue);
 246                 spin_unlock_irqrestore(&base->lock, flags);
 247                 if (!next)
 248                         continue;
 249                 delta = ktime_sub(next->expires, base->gettime());
 250                 if (!min.tv64 || (delta.tv64 < min.tv64))
 251                         min = delta;
 252         }
 253         if (min.tv64 == 0)
 254                 return 0;
 255
 256         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 257                 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
 258                 return -EBUSY;
 259         }
 260
 261         /* Setup an rtc timer to fire that far in the future */
 262         rtc_timer_cancel(rtc, &rtctimer);
 263         rtc_read_time(rtc, &tm);
 264         now = rtc_tm_to_ktime(tm);
 265         now = ktime_add(now, min);
 266
 267         /* Set alarm, if in the past reject suspend briefly to handle */
 268         ret = rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
 269         if (ret < 0)
 270                 __pm_wakeup_event(ws, MSEC_PER_SEC);
 271         return ret;
 272 }
 273
 274 static int alarmtimer_resume(struct device *dev)
 275 {
 276         struct rtc_device *rtc;
 277
 278         rtc = alarmtimer_get_rtcdev();
 279         if (rtc)
 280                 rtc_timer_cancel(rtc, &rtctimer);
 281         return 0;
 282 }
 283
 284 #else
 285 static int alarmtimer_suspend(struct device *dev)
 286 {
 287         return 0;
 288 }
 289
 290 static int alarmtimer_resume(struct device *dev)
 291 {
 292         return 0;
 293 }
 294 #endif
 295
 296 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 297 {
 298         ktime_t delta;
 299         unsigned long flags;
 300         struct alarm_base *base = &alarm_bases[type];
 301
 302         delta = ktime_sub(absexp, base->gettime());
 303
 304         spin_lock_irqsave(&freezer_delta_lock, flags);
 305         if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
 306                 freezer_delta = delta;
 307         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 308 }
 309
 310
 311 /**
 312  * alarm_init - Initialize an alarm structure
 313  * @alarm: ptr to alarm to be initialized
 314  * @type: the type of the alarm
 315  * @function: callback that is run when the alarm fires
 316  */
 317 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 318                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 319 {
 320         timerqueue_init(&alarm->node);
 321         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 322                         HRTIMER_MODE_ABS);
 323         alarm->timer.function = alarmtimer_fired;
 324         alarm->function = function;
 325         alarm->type = type;
 326         alarm->state = ALARMTIMER_STATE_INACTIVE;
 327 }
 328 EXPORT_SYMBOL_GPL(alarm_init);
 329
 330 /**
 331  * alarm_start - Sets an absolute alarm to fire
 332  * @alarm: ptr to alarm to set
 333  * @start: time to run the alarm
 334  */
 335 void alarm_start(struct alarm *alarm, ktime_t start)
 336 {
 337         struct alarm_base *base = &alarm_bases[alarm->type];
 338         unsigned long flags;
 339
 340         spin_lock_irqsave(&base->lock, flags);
 341         alarm->node.expires = start;
 342         alarmtimer_enqueue(base, alarm);
 343         hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 344         spin_unlock_irqrestore(&base->lock, flags);
 345 }
 346 EXPORT_SYMBOL_GPL(alarm_start);
 347
 348 /**
 349  * alarm_start_relative - Sets a relative alarm to fire
 350  * @alarm: ptr to alarm to set
 351  * @start: time relative to now to run the alarm
 352  */
 353 void alarm_start_relative(struct alarm *alarm, ktime_t start)
 354 {
 355         struct alarm_base *base = &alarm_bases[alarm->type];
 356
 357         start = ktime_add_safe(start, base->gettime());
 358         alarm_start(alarm, start);
 359 }
 360 EXPORT_SYMBOL_GPL(alarm_start_relative);
 361
 362 void alarm_restart(struct alarm *alarm)
 363 {
 364         struct alarm_base *base = &alarm_bases[alarm->type];
 365         unsigned long flags;
 366
 367         spin_lock_irqsave(&base->lock, flags);
 368         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 369         hrtimer_restart(&alarm->timer);
 370         alarmtimer_enqueue(base, alarm);
 371         spin_unlock_irqrestore(&base->lock, flags);
 372 }
 373 EXPORT_SYMBOL_GPL(alarm_restart);
 374
 375 /**
 376  * alarm_try_to_cancel - Tries to cancel an alarm timer
 377  * @alarm: ptr to alarm to be canceled
 378  *
 379  * Returns 1 if the timer was canceled, 0 if it was not running,
 380  * and -1 if the callback was running
 381  */
 382 int alarm_try_to_cancel(struct alarm *alarm)
 383 {
 384         struct alarm_base *base = &alarm_bases[alarm->type];
 385         unsigned long flags;
 386         int ret;
 387
 388         spin_lock_irqsave(&base->lock, flags);
 389         ret = hrtimer_try_to_cancel(&alarm->timer);
 390         if (ret >= 0)
 391                 alarmtimer_dequeue(base, alarm);
 392         spin_unlock_irqrestore(&base->lock, flags);
 393         return ret;
 394 }
 395 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
 396
 397
 398 /**
 399  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 400  * @alarm: ptr to alarm to be canceled
 401  *
 402  * Returns 1 if the timer was canceled, 0 if it was not active.
 403  */
 404 int alarm_cancel(struct alarm *alarm)
 405 {
 406         for (;;) {
 407                 int ret = alarm_try_to_cancel(alarm);
 408                 if (ret >= 0)
 409                         return ret;
 410                 cpu_relax();
 411         }
 412 }
 413 EXPORT_SYMBOL_GPL(alarm_cancel);
 414
 415
 416 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 417 {
 418         u64 overrun = 1;
 419         ktime_t delta;
 420
 421         delta = ktime_sub(now, alarm->node.expires);
 422
 423         if (delta.tv64 < 0)
 424                 return 0;
 425
 426         if (unlikely(delta.tv64 >= interval.tv64)) {
 427                 s64 incr = ktime_to_ns(interval);
 428
 429                 overrun = ktime_divns(delta, incr);
 430
 431                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
 432                                                         incr*overrun);
 433
 434                 if (alarm->node.expires.tv64 > now.tv64)
 435                         return overrun;
 436                 /*
 437                  * This (and the ktime_add() below) is the
 438                  * correction for exact:
 439                  */
 440                 overrun++;
 441         }
 442
 443         alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
 444         return overrun;
 445 }
 446 EXPORT_SYMBOL_GPL(alarm_forward);
 447
 448 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 449 {
 450         struct alarm_base *base = &alarm_bases[alarm->type];
 451
 452         return alarm_forward(alarm, base->gettime(), interval);
 453 }
 454 EXPORT_SYMBOL_GPL(alarm_forward_now);
 455
 456
 457 /**
 458  * clock2alarm - helper that converts from clockid to alarmtypes
 459  * @clockid: clockid.
 460  */
 461 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 462 {
 463         if (clockid == CLOCK_REALTIME_ALARM)
 464                 return ALARM_REALTIME;
 465         if (clockid == CLOCK_BOOTTIME_ALARM)
 466                 return ALARM_BOOTTIME;
 467         return -1;
 468 }
 469
 470 /**
 471  * alarm_handle_timer - Callback for posix timers
 472  * @alarm: alarm that fired
 473  *
 474  * Posix timer callback for expired alarm timers.
 475  */
 476 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 477                                                         ktime_t now)
 478 {
 479         unsigned long flags;
 480         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 481                                                 it.alarm.alarmtimer);
 482         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 483
 484         spin_lock_irqsave(&ptr->it_lock, flags);
 485         if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
 486                 if (posix_timer_event(ptr, 0) != 0)
 487                         ptr->it_overrun++;
 488         }
 489
 490         /* Re-add periodic timers */
 491         if (ptr->it.alarm.interval.tv64) {
 492                 ptr->it_overrun += alarm_forward(alarm, now,
 493                                                 ptr->it.alarm.interval);
 494                 result = ALARMTIMER_RESTART;
 495         }
 496         spin_unlock_irqrestore(&ptr->it_lock, flags);
 497
 498         return result;
 499 }
 500
 501 /**
 502  * alarm_clock_getres - posix getres interface
 503  * @which_clock: clockid
 504  * @tp: timespec to fill
 505  *
 506  * Returns the granularity of underlying alarm base clock
 507  */
 508 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
 509 {
 510         if (!alarmtimer_get_rtcdev())
 511                 return -EINVAL;
 512
 513         tp->tv_sec = 0;
 514         tp->tv_nsec = hrtimer_resolution;
 515         return 0;
 516 }
 517
 518 /**
 519  * alarm_clock_get - posix clock_get interface
 520  * @which_clock: clockid
 521  * @tp: timespec to fill.
 522  *
 523  * Provides the underlying alarm base time.
 524  */
 525 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
 526 {
 527         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 528
 529         if (!alarmtimer_get_rtcdev())
 530                 return -EINVAL;
 531
 532         *tp = ktime_to_timespec(base->gettime());
 533         return 0;
 534 }
 535
 536 /**
 537  * alarm_timer_create - posix timer_create interface
 538  * @new_timer: k_itimer pointer to manage
 539  *
 540  * Initializes the k_itimer structure.
 541  */
 542 static int alarm_timer_create(struct k_itimer *new_timer)
 543 {
 544         enum  alarmtimer_type type;
 545
 546         if (!alarmtimer_get_rtcdev())
 547                 return -ENOTSUPP;
 548
 549         if (!capable(CAP_WAKE_ALARM))
 550                 return -EPERM;
 551
 552         type = clock2alarm(new_timer->it_clock);
 553         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 554         return 0;
 555 }
 556
 557 /**
 558  * alarm_timer_get - posix timer_get interface
 559  * @new_timer: k_itimer pointer
 560  * @cur_setting: itimerspec data to fill
 561  *
 562  * Copies out the current itimerspec data
 563  */
 564 static void alarm_timer_get(struct k_itimer *timr,
 565                                 struct itimerspec *cur_setting)
 566 {
 567         ktime_t relative_expiry_time =
 568                 alarm_expires_remaining(&(timr->it.alarm.alarmtimer));
 569
 570         if (ktime_to_ns(relative_expiry_time) > 0) {
 571                 cur_setting->it_value = ktime_to_timespec(relative_expiry_time);
 572         } else {
 573                 cur_setting->it_value.tv_sec = 0;
 574                 cur_setting->it_value.tv_nsec = 0;
 575         }
 576
 577         cur_setting->it_interval = ktime_to_timespec(timr->it.alarm.interval);
 578 }
 579
 580 /**
 581  * alarm_timer_del - posix timer_del interface
 582  * @timr: k_itimer pointer to be deleted
 583  *
 584  * Cancels any programmed alarms for the given timer.
 585  */
 586 static int alarm_timer_del(struct k_itimer *timr)
 587 {
 588         if (!rtcdev)
 589                 return -ENOTSUPP;
 590
 591         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 592                 return TIMER_RETRY;
 593
 594         return 0;
 595 }
 596
 597 /**
 598  * alarm_timer_set - posix timer_set interface
 599  * @timr: k_itimer pointer to be deleted
 600  * @flags: timer flags
 601  * @new_setting: itimerspec to be used
 602  * @old_setting: itimerspec being replaced
 603  *
 604  * Sets the timer to new_setting, and starts the timer.
 605  */
 606 static int alarm_timer_set(struct k_itimer *timr, int flags,
 607                                 struct itimerspec *new_setting,
 608                                 struct itimerspec *old_setting)
 609 {
 610         ktime_t exp;
 611
 612         if (!rtcdev)
 613                 return -ENOTSUPP;
 614
 615         if (flags & ~TIMER_ABSTIME)
 616                 return -EINVAL;
 617
 618         if (old_setting)
 619                 alarm_timer_get(timr, old_setting);
 620
 621         /* If the timer was already set, cancel it */
 622         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 623                 return TIMER_RETRY;
 624
 625         /* start the timer */
 626         timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
 627
 628         /*
 629          * Rate limit to the tick as a hot fix to prevent DOS. Will be
 630          * mopped up later.
 631          */
 632         if (ktime_to_ns(timr->it.alarm.interval) < TICK_NSEC)
 633                 timr->it.alarm.interval = ktime_set(0, TICK_NSEC);
 634
 635         exp = timespec_to_ktime(new_setting->it_value);
 636         /* Convert (if necessary) to absolute time */
 637         if (flags != TIMER_ABSTIME) {
 638                 ktime_t now;
 639
 640                 now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
 641                 exp = ktime_add_safe(now, exp);
 642         }
 643
 644         alarm_start(&timr->it.alarm.alarmtimer, exp);
 645         return 0;
 646 }
 647
 648 /**
 649  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 650  * @alarm: ptr to alarm that fired
 651  *
 652  * Wakes up the task that set the alarmtimer
 653  */
 654 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 655                                                                 ktime_t now)
 656 {
 657         struct task_struct *task = (struct task_struct *)alarm->data;
 658
 659         alarm->data = NULL;
 660         if (task)
 661                 wake_up_process(task);
 662         return ALARMTIMER_NORESTART;
 663 }
 664
 665 /**
 666  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 667  * @alarm: ptr to alarmtimer
 668  * @absexp: absolute expiration time
 669  *
 670  * Sets the alarm timer and sleeps until it is fired or interrupted.
 671  */
 672 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
 673 {
 674         alarm->data = (void *)current;
 675         do {
 676                 set_current_state(TASK_INTERRUPTIBLE);
 677                 alarm_start(alarm, absexp);
 678                 if (likely(alarm->data))
 679                         schedule();
 680
 681                 alarm_cancel(alarm);
 682         } while (alarm->data && !signal_pending(current));
 683
 684         __set_current_state(TASK_RUNNING);
 685
 686         return (alarm->data == NULL);
 687 }
 688
 689
 690 /**
 691  * update_rmtp - Update remaining timespec value
 692  * @exp: expiration time
 693  * @type: timer type
 694  * @rmtp: user pointer to remaining timepsec value
 695  *
 696  * Helper function that fills in rmtp value with time between
 697  * now and the exp value
 698  */
 699 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
 700                         struct timespec __user *rmtp)
 701 {
 702         struct timespec rmt;
 703         ktime_t rem;
 704
 705         rem = ktime_sub(exp, alarm_bases[type].gettime());
 706
 707         if (rem.tv64 <= 0)
 708                 return 0;
 709         rmt = ktime_to_timespec(rem);
 710
 711         if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
 712                 return -EFAULT;
 713
 714         return 1;
 715
 716 }
 717
 718 /**
 719  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 720  * @restart: ptr to restart block
 721  *
 722  * Handles restarted clock_nanosleep calls
 723  */
 724 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 725 {
 726         enum  alarmtimer_type type = restart->nanosleep.clockid;
 727         ktime_t exp;
 728         struct timespec __user  *rmtp;
 729         struct alarm alarm;
 730         int ret = 0;
 731
 732         exp.tv64 = restart->nanosleep.expires;
 733         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 734
 735         if (alarmtimer_do_nsleep(&alarm, exp))
 736                 goto out;
 737
 738         if (freezing(current))
 739                 alarmtimer_freezerset(exp, type);
 740
 741         rmtp = restart->nanosleep.rmtp;
 742         if (rmtp) {
 743                 ret = update_rmtp(exp, type, rmtp);
 744                 if (ret <= 0)
 745                         goto out;
 746         }
 747
 748
 749         /* The other values in restart are already filled in */
 750         ret = -ERESTART_RESTARTBLOCK;
 751 out:
 752         return ret;
 753 }
 754
 755 /**
 756  * alarm_timer_nsleep - alarmtimer nanosleep
 757  * @which_clock: clockid
 758  * @flags: determins abstime or relative
 759  * @tsreq: requested sleep time (abs or rel)
 760  * @rmtp: remaining sleep time saved
 761  *
 762  * Handles clock_nanosleep calls against _ALARM clockids
 763  */
 764 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 765                      struct timespec *tsreq, struct timespec __user *rmtp)
 766 {
 767         enum  alarmtimer_type type = clock2alarm(which_clock);
 768         struct alarm alarm;
 769         ktime_t exp;
 770         int ret = 0;
 771         struct restart_block *restart;
 772
 773         if (!alarmtimer_get_rtcdev())
 774                 return -ENOTSUPP;
 775
 776         if (flags & ~TIMER_ABSTIME)
 777                 return -EINVAL;
 778
 779         if (!capable(CAP_WAKE_ALARM))
 780                 return -EPERM;
 781
 782         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 783
 784         exp = timespec_to_ktime(*tsreq);
 785         /* Convert (if necessary) to absolute time */
 786         if (flags != TIMER_ABSTIME) {
 787                 ktime_t now = alarm_bases[type].gettime();
 788                 exp = ktime_add(now, exp);
 789         }
 790
 791         if (alarmtimer_do_nsleep(&alarm, exp))
 792                 goto out;
 793
 794         if (freezing(current))
 795                 alarmtimer_freezerset(exp, type);
 796
 797         /* abs timers don't set remaining time or restart */
 798         if (flags == TIMER_ABSTIME) {
 799                 ret = -ERESTARTNOHAND;
 800                 goto out;
 801         }
 802
 803         if (rmtp) {
 804                 ret = update_rmtp(exp, type, rmtp);
 805                 if (ret <= 0)
 806                         goto out;
 807         }
 808
 809         restart = &current->restart_block;
 810         restart->fn = alarm_timer_nsleep_restart;
 811         restart->nanosleep.clockid = type;
 812         restart->nanosleep.expires = exp.tv64;
 813         restart->nanosleep.rmtp = rmtp;
 814         ret = -ERESTART_RESTARTBLOCK;
 815
 816 out:
 817         return ret;
 818 }
 819
 820
 821 /* Suspend hook structures */
 822 static const struct dev_pm_ops alarmtimer_pm_ops = {
 823         .suspend = alarmtimer_suspend,
 824         .resume = alarmtimer_resume,
 825 };
 826
 827 static struct platform_driver alarmtimer_driver = {
 828         .driver = {
 829                 .name = "alarmtimer",
 830                 .pm = &alarmtimer_pm_ops,
 831         }
 832 };
 833
 834 /**
 835  * alarmtimer_init - Initialize alarm timer code
 836  *
 837  * This function initializes the alarm bases and registers
 838  * the posix clock ids.
 839  */
 840 static int __init alarmtimer_init(void)
 841 {
 842         struct platform_device *pdev;
 843         int error = 0;
 844         int i;
 845         struct k_clock alarm_clock = {
 846                 .clock_getres   = alarm_clock_getres,
 847                 .clock_get      = alarm_clock_get,
 848                 .timer_create   = alarm_timer_create,
 849                 .timer_set      = alarm_timer_set,
 850                 .timer_del      = alarm_timer_del,
 851                 .timer_get      = alarm_timer_get,
 852                 .nsleep         = alarm_timer_nsleep,
 853         };
 854
 855         alarmtimer_rtc_timer_init();
 856
 857         posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
 858         posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
 859
 860         /* Initialize alarm bases */
 861         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 862         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 863         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 864         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 865         for (i = 0; i < ALARM_NUMTYPE; i++) {
 866                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 867                 spin_lock_init(&alarm_bases[i].lock);
 868         }
 869
 870         error = alarmtimer_rtc_interface_setup();
 871         if (error)
 872                 return error;
 873
 874         error = platform_driver_register(&alarmtimer_driver);
 875         if (error)
 876                 goto out_if;
 877
 878         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 879         if (IS_ERR(pdev)) {
 880                 error = PTR_ERR(pdev);
 881                 goto out_drv;
 882         }
 883         ws = wakeup_source_register("alarmtimer");
 884         return 0;
 885
 886 out_drv:
 887         platform_driver_unregister(&alarmtimer_driver);
 888 out_if:
 889         alarmtimer_rtc_interface_remove();
 890         return error;
 891 }
 892 device_initcall(alarmtimer_init);